Theoretical and experimental investigation of the performance of back-pass solar air heaters

Abstract

This paper presents a study dealing with the experimental and theoretical analysis of a flat plate solar air heater. The air collectors were tested experimentally for the tilt angle of 35° and 2 m s −1 air velocity, and ambient temperature, inlet temperature, outlet temperature, absorber plate temperature, bottom plate temperature, solar radiation, air velocity, and airflow velocity from the duct were measured. The outlet air temperature and energy and exergy efficiencies of the collector were calculated theoretically. The results showed that the collector has the maximum mean outlet temperature for the airflow velocity of 1 m s −1, duct height of 0.001 m, triple glass cover, and length of 3 m; the maximum mean energy efficiency for the airflow velocity of 4 m s −1, duct height of 0.04 m, triple glass cover, and length of 1 m; and the maximum mean exergy efficiency for the airflow velocity of 1 m s −1, duct height of 0.005 m, triple glass cover, and length of 3 m. This study demonstrated the superiority of exergy analysis over energy analysis before the decision regarding design parameters.